1. Field of the Invention
The present invention relates to a package encasing a high-frequency device such as an MIC (Microwave Integrated Circuit) or an MMIC (Microwave Monolithic Integrated Circuit).
2. Description of the Related Art
FIG. 1 of the accompanying drawings shows in perspective a conventional high-frequency device package which encases an MIC therein.
As shown in FIG. 1, the high-frequency device package includes a base 102 on which an MIC 101 and film circuit boards 116 are soldered. Each of the film circuit boards 116 comprises an adjustment circuit, a filter circuit, a balun circuit, etc. formed on a ceramic board by the thin film technology. Chip capacitors 103 are also mounted on the base 102.
Power supply terminals 104 and signal terminals 115 for connection to circuits external to the high-frequency device package extend transversely through the base 102 in hermetically sealed relation thereto. The power supply terminals 104 are electrically connected to the chip capacitors 103, respectively, by bonding wires 117, and the chip capacitors 103 are electrically connected to the film circuit boards 116 by bonding wires 117. The film circuit boards 116 are electrically connected to the MIC 101 by bonding wires 117. The signal terminals 115 are electrically connected to the film circuit boards 116 by bonding wires 117. Therefore, electric energy from an external power supply (not shown) and input signals from an external circuit are supplied through the terminals 104, 115 to the MIC 101. Output signals processed in the high-frequency device package are also led through the terminals 115 to the external circuit. Since the power supply terminals 104 and the MIC 101 are connected to each other through the chip capacitors 103, high-frequency signals are prevented from leaking out of the high-frequency device package through the power supply terminals 104.
The surface of the base 102 on which the MIC 101 and other components are mounted is hermetically sealed by a cap 106 to protect the MIC 101 and other components from humidity and dust. The cap 106 is made of metal such that it electrically shields the MIC 101 and other components. The cap 106 may be brazed or welded to the base 102 to hermetically seal the MIC 101 and other components on the base 102.
Many electronic devices which incorporate high-frequency devices such as MICs are available for personal use, and there are demands for making those electronic devices less expensive. However, conventional high-frequency device packages have suffered various difficulties that prevent their cost from being reduced, as described below.
First, since the components in the high-frequency device packages are electrically connected by bonding wires, each electrode or contact has to be connected by an individual bonding wire. As a result, the number of required bonding steps is very large.
Secondly, the components on the base of the high-frequency device packages need to be hermetically sealed by the cap in a nitrogen atmosphere with high positional accuracy. Such a sealing process must be carried out by a special piece of equipment.